2,2-disubstituted 1,2-dihydro-3H-indol-3-one (trivially known as pseudo indoxyl) is one of the important structural units present in many natural products and biologically active small molecules1. Apart from their use as intermediates in the synthesis of natural products, in recent years, the indol-3-one derivatives have also found important applications in the areas of fluorescence dyeing and in solar cell applications.
Rearrangement of 2,3-dihydroxyindolines and 3H-indol-3-ols (acid-, base-, or thermal-induced) is one of the earlier methods reported for the preparation of indoxyl derivatives. The oxidative rearrangements of 2,3-disubstituted indoles or the tetrahydrocarbolines is one of more popular methods used in the synthesis of the indoxyl class of natural products. The addition of Grignard reagents to 2-arylindolone followed by the acid catalysed pinacol rearrangement, as well as the addition of carbon cantered nucleophiles to spiro[furan/pyran-2,2′-indolin]-3′-ones are some of the methods which offer the provision to vary the substituents at the C(2) position.
The CuI catalyzed intramolecular amination, an interrupted Ugi reaction comprising of an internal attack of the electron rich aromatic ring on an electrophilic nitrilium ion, the gold-mediated cycloisomerization of 2-alkynyl aryl azides, the Mannich/Henry reaction of cyclic α-carbonyl ketimines and the reaction of amino acids with arynes are some of the other methods that have been developed recently for synthesis of 2,2-disubstituted indolin-3-ones.
In 1979, Ardakani and Smalley in M. A. Ardakani and R. K. Smalley, Tetrahedron Lett., 1979, 20, 4769; reported the base induced intramolecular cyclization of αazidophenyl sec-alkyl ketones leading to 2,2-disubstituted indolin-3-ones trivially known as the Smalley cyclization (eq. 1, Scheme 1). This reaction has served as the key step in the total synthesis of lapidilectineB. The substrates that are generally used for the Smalley Rearrangement require free fabricated α-azidophenyl sec-alkyl ketones.
WO 2012081893 A2 discloses the marked derivatives 3-indole rinon, the following formula 1 or 2, or his or her salt:

R1 is hydrogen, C1-6 alkoxy, C1-4 alkyl, substituted or unsubstituted C2-6 alkenyl, oxy, benzyloxy or C1-4 alkoxy, and phenyl; R2 is C1-6 alkyl; R3 and R4 are each independently hydrogen, C1-6 alkyl, C1-4 alkyl, substituted or unsubstituted C2-6 alkenyl, C2-6 alkynyl, benzyl, or C3-6 cycloalkyl methyl; R5 is a substituted or unsubstituted C1-6 alkyl, C1-4 alkyl, C2-6 alkenyl or C3-6 cycloalkyl methyl.
Regiodivergent Annulation of Alkynyl Indoles To Construct Spiro-pseudoindoxyl and Tetrahydro-β-carbolines by Yong-Qiang Zhang et. al in Org. Lett., 2011, 13 (13), pp 3458-3461 reports Regiodivergent annulations of 3-phenoxy alkynyl indoles have been developed and tuned by protective groups through gold catalysis. With electron-donating protective groups, the substrate followed a C3-selective annulation and gave structurally interesting tetrahydro-β-carboline derivatives possessing potential bioactivity. Using electron-withdrawing protective groups, the substrate underwent a C2-selective annulation and afforded the structurally useful spiro-pseudoindoxyl found in natural indole alkaloids. Notably, an interesting and unusual 1,2-migration of the phenoxy group was found in the C3-selective process.
However, the reported methods adopted multistep sequences with harsh reaction conditions in some particular cases.
The present inventors have recently documented one pot SNAr-click reaction of fluoronitrobenzenes with azide nucleophile for synthesis of 1,4 substituted triazoles. It is further reported that if there is no dipolarophile to trap the azide, these intermediate azide are reduced further to anilines. With the current interest to provide a more feasible, cost effective process for the synthesis of natural products having the indolin-3-one core, the invention is directed to provide a process using one-pot [Cu]-catalysed SNAr and the Smalley rearrangement of α-halophenyl sec-alkyl ketones.